Influência do método de vulcanização nas propriedades mecânicas e na densidade de ligações cruzadas da borracha natural

Oliveira, Maria Aparecida de; Cassu, Silvana Navarro; Mello, S. A. C.; Dutra, Jorge Carlos Narciso

doi:10.1590/0104-1428.2051

Cited by 12 publications

(17 citation statements)

References 14 publications

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“…Oliveira et al . demonstrated that the density of polysulphidic links was reduced as the time of samples under pressure and temperature in a hydraulic press increased, corroborating with the results obtained in the present work.…”

Section: Mechanical Propertiessupporting

confidence: 93%

“…Crosslinking density is an important factor that affects the physical properties of the vulcanized elastomer . Related to this, the influence of density and crosslinking type in the mechanical properties of rubber has been studied by various authors, since the stress‐strain measurement is an indirect method for determining the crosslinking density …”

Section: Introductionmentioning

confidence: 99%

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Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Sousa

Zanchet

Scuracchio

2017

J of Applied Polymer Sci

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The influence of rubber devulcanization by microwaves in the reversion behavior is still modestly explored in the literature. The reversion occurs due to thermal degradation of unstable crosslinkings formed during the vulcanization process. This phenomenon results in poor final mechanical properties of the artifacts. In this work, some formulations based on natural rubber (NR) with the incorporation of NR devulcanized by microwaves at different exposure times to the microwaves were vulcanized by compression molding at the same temperature and time used for the study of their vulcanization characteristics, in order to correlate the properties obtained and understand the influence of the reversion on the mechanical properties. The results showed that levels of devulcanization/degradation of the recycled phase, as well as the additional heating time influenced on the behavior of reversion and, consequently, on the mechanical properties. the influence of density and crosslinking type in the mechanical properties of rubber has been studied by various authors, 4,6,7 since the stress-strain measurement is an indirect method for determining the crosslinking density. 5Currently, a big global problem is related to disposal of solid urban residues, and materials able to make this problem much worse are the vulcanized/cured elastomers. In the same way, the search for processes and/or sustainable materials is of great value, and it is directly related to the solution of this problem, since the use of recycled materials can reduce such problem. In addition, recycling not only protects the environment, but also saves the limited petroleum resources from which the raw material originates, 8 also being a source of income for many families around the world. The recycling method used in this work is the devulcanization by microwaves.Devulcanization is a way of providing energy to destroy, total or partially, the three-dimensional network formed during vulcanization. 9 Devulcanization by microwaves is a well-established recycling technique of vulcanized elastomers. Among its

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Section: Mechanical Propertiessupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Sousa

Zanchet

Scuracchio

2017

J of Applied Polymer Sci

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“…Tensile strength and elongation at break results of the samples are shown in Figure 2. The tensile strength results of the EPDM-r samples (Figure 2a) were in accordance with the values observed in Table 4 for MH, indicating that the increase of the cross-link density led to the observed increase of the tensile strength [36]. The tensile strength of the sample EPDM-r 30 was The tensile strength results of the EPDM-r samples (Figure 2a) were in accordance with the values observed in Table 4 for MH, indicating that the increase of the cross-link density led to the observed increase of the tensile strength [36].…”

Section: Mechanical Propertiessupporting

confidence: 86%

“…The tensile strength results of the EPDM-r samples (Figure 2a) were in accordance with the values observed in Table 4 for MH, indicating that the increase of the cross-link density led to the observed increase of the tensile strength [36]. The tensile strength of the sample EPDM-r 30 was The tensile strength results of the EPDM-r samples (Figure 2a) were in accordance with the values observed in Table 4 for MH, indicating that the increase of the cross-link density led to the observed increase of the tensile strength [36]. The tensile strength of the sample EPDM-r 30 was higher than that of the Control sample, indicating that 30 phr of EPDM-r can be added to the formulation without compromising the mechanical behavior of the composition.…”

Section: Mechanical Propertiessupporting

confidence: 86%

The Influence of UV-Accelerated Aging Process on Industrial Waste Containing EPDM

et al. 2019

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One of the most efficient ways to recycle elastomeric residues from industrial processes is to incorporate them into compositions. The study of these new compositions is interesting in terms of reducing cost, the consumption of raw materials, and the generation of new waste, working towards sustainable development. Thus, this research aimed to produce and characterize elastomeric blends containing one phase comprised of ethylene-propylene-diene monomer rubber (EPDM) industrial waste aged by the action of ultraviolet radiation (UV) in a UV chamber, and the other comprised of raw EPDM, containing different concentrations of residue. Therefore, the mechanical properties and the vulcanization characteristics of the blends containing different concentrations of EPDM residue-aged and un-aged-were analyzed and compared to the properties of a standard formulation (Control). The results showed that the aging of the waste for a period of 156 h did not trigger a severe degradation process. Additionally, its reuse into new compositions promoted improvements of the studied mechanical properties without compromising the vulcanization characteristics due to the higher molecular stiffness of the samples. This procedure can be used to lower costs, but only small amounts of residue can be incorporated into raw rubber without altering the material properties, due to the weak interaction of vulcanized rubber with raw rubber [1,2,5]. Some methods aim to improve this interaction by de-vulcanization. Among the most-studied methods, the ultrasound method uses ultrasound waves to produce cavitation in the rubber, which generates tensions that are able to break the chemical bonds [3,5,[11][12][13][14][15][16][17][18]. Another de-vulcanization method based on the action of microwaves presents some advantages that make it one of the most promising for the recycling of rubber [2][3][4]13,15,[18][19][20][21][22], including its physical nature, the volumetric heating of the material by the microwaves, and the possibility of high productivity [23].The aging of elastomers can be defined as the degradation process produced by the interaction between a material and an environment, modifying their structure and properties (i.e., mechanical, electrical, chemical, and/or thermal). It is a complex chemical process that occurs under the influence of heat, oxygen, light, ozone, and mechanical tension, and it results in time-dependent modifications of the chemical and physical properties [24]. In elastomeric compositions, the term "aging" is related to molecular scission, which results in smaller chains, a larger number of chain terminals, and/or cross-link formation, which generates a strong linked network structure [16]. UV radiation is one of the most effective means for the degradation of organic materials through photo-oxidation. This radiation causes irreversible chemical modifications that affect the mechanical properties of materials. UV degradation can make materials brittle, lose resistance, and induce color change, affecting the lifetime of ma...

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“…The elastomers subjected to the vulcanization process with sulfur exhibit physical, mechanical, and chemical changes due to the modification of its plastic state to the elastic state resulting from the formation of crosslinks between the polymer chains . In addition, the vulcanization kinetics may be altered by the use of accelerators, which are intended to improve the efficiency of crosslinks that occur during the vulcanization step .…”

Section: Introductionmentioning

confidence: 99%

Comparative study among TMTD, TBzTD, and ZBEC accelerators in isobutylene‐isoprene elastomer vulcanization

Gobbi

Silva

Cunha

et al. 2020

J of Applied Polymer Sci

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Accelerators such as tetramethylthiuram disulfide (TMTD) are responsible for releasing nitrosamines, considered carcinogenic by international organizations. Tetrabenzylthiuram disulfide (TBzTD) and zinc dibenzyldithiocarbamate (ZBEC) are indicated as substituents of TMTD for not releasing noxious nitrosamines. Thus, the objective of this work was to compare the use of TMTD, TBzTD, and ZBEC accelerators in the production of isobutylene-isoprene rubber compounds. It was evaluated the effect of TBzTD/mercaptobenzothiazole and ZBEC/ N-cyclohexyl-2-benzothiazolesulfenamide pairs in the rheological properties and the first pair achieved better results. Subsequently, it was evaluated compounds containing TBzTD and ZBEC accelerators separately. The experimental design data of the obtained maximum torque were correlated by an interpolation method (thin-plate spline interpolation method). Physical-mechanical and thermodynamic measurements showed a decrease in the mechanical properties of TBzTD and ZBEC compounds. Thermogravimetric analysis did not indicate thermal differences between the compounds, Fourier transform infrared and swelling degree analyses corroborated the difference found in the crosslink densities of the compounds.

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Influência do método de vulcanização nas propriedades mecânicas e na densidade de ligações cruzadas da borracha natural

Cited by 12 publications

References 14 publications

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

Influence of reversion in compounds containing recycled natural rubber: In search of sustainable processing

The Influence of UV-Accelerated Aging Process on Industrial Waste Containing EPDM

Comparative study among TMTD, TBzTD, and ZBEC accelerators in isobutylene‐isoprene elastomer vulcanization

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